Pump-oxygenator



y March 8, 1960 J. w ABERKMAN ErAL 2,927,582

INVENTORS :rom m. BERKMAN R\CHARD E. 'JONES BY PAUL D. SENSTAD 1977OBA/EY March 8, 1960 J. w. BERKMAN ErAL 2,927,582

PUMP-OXYGENATOR Filed March 19, 1956 8 Sheets-Sheet 3 T0 VENDUS RESERVO\R 1N VENTORS SOHN w- BEEKMAN RNLRRRD E- TUNES /QM UAW #PIURA/EY March 8,1960 Filed March 19, 195e J. W. BERKMAN I'AL 2,927,582 PUMP-OXYGENATOR 8Sheets-Sheet 4 l 9 I 7. l I] Q4 *n 4 L 24a F ZBO WBV.

SIGNAL FROM P. E. CELL PRE-AMPLIFIER lllllllllli- INVENTORS KUHN BERKMRNE\CHF\RD E. SONES PAUL. D. SENSTAB Hyde/Vey March 8, 1960 i Filed March19, 1956 J. w. BERKMAN ETAL PUMP-OXYGENATOR LL-J a4 sa ma,

8 Sheets-Sheet. 5

EETUBE a4 QR es RUBBER DRPRRRGM INVENTORS BY PPN L D- SENSTAD March 8,1960 J. w. BERKMAN ETAL 2,927,582

PUMP-OXYGENATOR Filed March 19, 1956 8 Sheets-Sheet 7 I ugv- P E WEEAmm/verl MarCh 8, 1960 J. w. BERKMAN l-:TAL 2,927,582

PUMP-OXYGENATOR 8 Sheets-Sheet 8 Filed March 19, 1956 mwa .u B mim Emmumvrm We u A dr uA J Ies a mun/. R.. E M

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United States Patent O" PUMP-OXYGENATOR John W. Berkman and Richard E.Jones, Rochester, and Paul D. Senstad, Minneapolis, Minn., assignors, bymesne assignments, to Research Corporation, New York, N.Y., acorporation of New York Application March 19, 1956, Serial No. 572,389

18 Claims. (Cl. 12S-214) This invention relates to improved devices,capable of assuming the functions of the heart and lungs of a humanbeing, during such period as may be required for exposing the chambersof the heart to the direct vision of the surgeon, for performance ofcorrective thoracic surgery. For convenience in nomenclature suchapparatus, in its entirety, is called a Pump-Oxygenator.

The art of thoracic surgery was much advanced by the work of Johnv H.Gibbon and his co-workers. paratus, developed and perfected by them foruse in such surgery, is covered by U.S. Patents 2,659,368; 2,705,493 andrelated patents. It is in respect to apparatus of this type that thepresent invention forms an improvement.

In the Gibbon et al. apparatus venous blood from the patient iswithdrawn by a pump, denoted a venous pump, :and the .blood isdelivered, in some instances by an additional pump into an oxygenator,from which it is withdrawn by an artery pump and returned to thepatient. 'The blood circulated thru the oxygenator includes not lonlythat which is withdrawn from the patient but also :a certain amount maybe recirculated, some of that which is recirculated being blood from theartery delivery sys- `tem which is returned back to the vein pumpsystem. lThe amount of blood so recirculated is manually adfjusted inthe Gibbon apparatus.

We have found that optimum venous blood withdrawal from the patient isobtained and that danger of collapse of the patients veins is minimizedwhen an improved venous blood withdrawal system is utilized, and it isan object of the present invention to provide such`improvements. Moreparticularly it is an object of the invention to provide an improvedpump-oxygenator wherein the venous blood withdrawal from the patient isby virtue of a system of apparatus in which a closely regulated pressureis maintained, at a pressure level such that when venous blood cannulaor cannulas are connected to the patient there will be maintained, atthe point of blood withdrawal in the central venous system of thepatient, a pressure within the range of, and preferably approximatingthe mean pressure of, said venous system during normal physiology of thepatient as determined by preoperative measurements of such centralvenous pressure.

In the prior art systems of which this invention con stitutesimprovement, some recirculation of partially or completely oxygenatedblood thru the oxygenator segment of the system was used, but the amountor proportion of such recirculated blood as compared to the venous bloodinflow was either not regulated at all or was manually adjustedarbitrarily. It has been discovered that the venous blood inow from thepatient and arterial blood delivery to the patient vary at differentstages of the surgical procedure and it is the desideratum that such maybe conveniently accommodated, and that with in minor limits of ratevariation, the amount of arterial blood returned should equal the amountof venous blood withdrawn. It is an object of this invention to providean improved pump-oxygenator apparatus accommodat- The ap-f 2,927,582Patented .Main 8, 1960 ing these requisites and more especially toprovide, autol.

matically land continuously to adjust the amount ofrecirculated blood soas to maintain substantially constant the volume of blood passed thruthe oxygenator, while automatically accommodating variations of inow anddelivery to the patient.

In thoracic surgery a cardiotomy is performed in order that the surgeonmay complete the delicate repairs needed. During such, rthe vheartcontinues to beat, and its own blood supply, which is normally returnedby the cor-' onary sinuses is lost thru the resected organ. With theheart resected and according to prior surgical procedures, the bloodsupply of the heart itself was collected,

usually by a vacuum system, and was then rejected from One'- reason forthis was because vacuum collection not only` draws in the blood returnedby the coronary sinuses butv also a certain amount of air from the openpatient, and.` bubbles and foam resulted in such collected blood. As. nomeans has heretofore been available for safely sep? arating the bubblesand foam, and as the amount of the recirculatory system of thepump-oxygenator.

blood thus lost, while appreciable, was not excessive, it

has beenrthe practice to reject such intermixed blood, and,

bubbles `and to make up the loss by donation. j

lt is an object of this invention to provide an improvedvpump-oxygenator in which the coronary sinus blood is collected,separated from air which is inevitably also drawn in, and safelyreturned to the system.

Other and further objects are those inherent in the anism which formsone segment of the pump-oxygenator organization;

Figure 4 is related to Figure 3, and in part showsa vertical sectionalview taken along the line and inthe direction of arrows 4--4 of Figure3. The circuits shown in Figure 4 are for the occluder valve mechanismcontrol; Y

Figure 5 is a vertical sectional view of a photo-electric liquid levelcontrol apparatus of the type utilized at sev'- eral locations ascomponents in the pump-oxygenator apparatus; Y A' Figure 6 is ahorizontal sectional view taken along the line and in the direction ofarrows 5-5 of Figure 5;

Figure 7 is a wiring diagram of the occluder-valve f mechanism motormechanism controls; v

Figure 8 is a wiring diagram of the artery pump motor mechanismcontrols;

Figure 9 is a wiring diagram of the vacuum valve mechanism motor and itsassociated controls.

Throughout the drawings corresponding numerals refer to the sameelements. y

Referring to the drawings, Figures 1A and 1B when arranged side-by-sidewith Figure 1A at the left and Figure 1B at the right show the entirepump-oxygenator system. When operating, venous blood is received fromthe patient at line i0 which passes junctions 11 and 12 and enters port14 in the top of venous reservoir generally designated 15. Venousreservoir 15 is preferably made of Lucite. It has a top wall in whichports 14, 16, 18 and 19 are provided. Port 14 has an extension reachingdown into the reservoir aligned with the upper cocasse v.

tip of an inverted top-shaped liquid spreader 20 which.

has a bottom slightly convert downwardl which intersects the normalliquid level line 24. This construction reduces. velocity of bloodinflow and discourages splashing.-

rI `l1e-venous blood rese-rvoir upper cavity 21 is necked in at 22 toblend smoothly into the smaller lower cavity 23. Side ports 25, 26 and27 are provided in the walls offthe lower cavity as shown. Port 27r islargest and is provided with a very flexible rubber diaphragm 28, whichseparates the blood in the reservoir from a 'clear liquid at 8,0, whichstands in riser 77.

' From port 16, line 29 extends to port. 30 in the coro nary sinusreservoir generally designated'l. This reservoir has an upper part 32which'curves in as shown along the bottom 34. In the solid bottom 35there are an entrance riser 36 vhaving a plastic excelsior material38`which is surface treated with an anti-foam chemical. The. coronaryinow of blood, air, foam and bubbles is introduced thru port 39, riser36 and the material 38, andthe air component of the mixture ofl blood,foam and bubbles is caused to separate from the liquid blood whichstabilizes at level 24, the air being drawn thru line 29 to reservoir 1Sand then to vacuum line 13. A portv 39 connects to the bottom end ofriser 36 and extends thru a plastic tube which forms a part of pump 4Dand then on at' 41, which is the coronary sinus sucker line. The end ofline 41 is located by the surgeon at an appropriate place in theresected` heart, so as' to suck in the venous blood of that organ, whichis liberated by the exigencies of surgical procedure. Air is also drawnin by such sucking operation. The pump' 40 is of the general types shownin Patents 2,659,368 and 2,705,493. It is driven by shaft 42 thru amanually adjustable variable-speed drive 44 from motor 45 which ispreferably a; polypose induction motor. Pump 40 produces the onlyelective suction on line 41 and serves to regulate the volumetric rateof total flow thru the coronary sinus sucker line 41. Pump 40 preventsthe unrestricted inflow of air, into line 41 as would occur if a vacuum'should be connected directly to the coronary suckerline. Pump 40, ineiect, acts as a rotary gate which permits only a certain (adjusted)volume inflow into line 41,. andthus greatly restricts the inflow ofunwanted air.

Venous input reservoir and the coronary sinus reser- K voirY 31 areconnected together above the liquid level 24 by line 29 and connectedtogether below the liquid. level by line 23 which enters the bottom oithe well 37 of the. coronary sinus reservoir. .The venous inputreservoir 15v is evacuated to a controlled negative pressure, via line18, Yand such negative pressure is communicated via line 29 to reservoir31. An admixture of blood, bubbles and foam thru line 41 and pump 40enters reservoir 31 thru riser 36 and in passing thru material 33 is encouraged to separate into its liquid blood and air com ponents, the airrising to surface 24 and there separating, being drawn oit via line 29,space 21, and line 18. Since the liquid (blood) leaves by down-How inwell 37, bubbles of air (which want to rise) are discouraged from beingentramed and easily separate from the iiow in 37, since the .rate of owis very slow.

From port 18 of the venous reservoir 15, a line 46 extends to a vacuumcontrol valve generally designated.

48. The portion shown within the dotted square 43 of Figure l, isillustrated in greater detail in Figures 2 or 9 to which reference isnow made. The vacuum control valve includes a chamber 49 havingconnected thereto an unregulated vacuum supply line 56 and a regulatedvacuum line at 46. To line 56 there is attached a vacio um supply ofSOO-600 mm. of Hg capacity. An ordinary laboratory type venturi vacuumdevice connected to a water tap is suicient to s upply adequate vacuumand capacity. The hollow chamber 49 has a at top thru which a taperedair bleeder opening 50 (generated arcuately) is made.

which is shaped as shown in Figure 2, is mountedon The rotary bladevalve element 51,l

shaft 63, and fits snugly against the upper planar surface of` chamber49`. Itis arranged to rotate in either direction within the limits ofstop 57 as shown by double arrow 47, via gears 52 and slip clutch 53from shaft 54 of reversible motor 55. Manual rotation via gear 62 andhandle 64 is provided. The width of slot 50 decreases in the clockwisedirection (as viewed in Figure 2) and as edge 51A moves. clockwise, thestill uncovered (and hence still effective) area of slot 50 will bedecreased. When edge 51A engages stop S7 slot50 is entirely closed.4When edge 51B engages stop 57, slot 5t] is entirely open. The open areaof slot 50 acts as. a bleeder port, which regulates the net vacuum drawnon line 46; When slot 50 is closed' the entire vacuum capacity of line56 is applied to line 46;. when entirely open atmospheric air, drawnthru the slot 50 greatly reduces the effectiveness of vacuum line 56upon line 46. Regulation of vacuumV is achieved by-varying the size ofthe uncovered area of slot 50'.

The motor 55 is a standard polyphase reversible instrw' f ment-typemotor which is connected by its four leads 58-61 to motor controlamplier power supply system generally designated 62. The motor 48 andthe motor control power sup-ply amplifier system 62 are each stand-l ardarticles of manufacture, the details of which, per se, form` no part ofthis invention. It is'sufiicient here to say that system 62 is supplied"with alternating current' power of standard voltage and frequency vialines L1 andl L2 and is connected via four terminals to lines 58-61leading to motor 55. Two signal input terminals 64' and 65 (here vacuumamount signal), of the control 66 are connected to opposite corners 68and 69 of a Wheatstone bridge which is a component of a strain gaugegenerallyl designated 66. VThis strain gauge 66 is likewise a standardarticle of manufacture, yand con-- tains a vacuum responsive diaphragm70, connected by post 71 to the Wheatstone bridge, the latter beingsup-v plied by a low voltage direct current potential such as battery72. The diaphragm chamber of strain gauge" vacuum responsive signalelement 66 is connected via line 74 to port 19 of the venous reservoir15, and is re sponsive to the vacuum in such reservoir. The controlamplilicr and power supply has a manual regulator 75. When the vacuumlvaries in the venous reservoir 15, a unidirection voltage signal whichis a function of suchvacuum amount is` generated at gauge 66 and appliedtov input terminals 64 and 65 of the unit 62. The latter unit applies'an appropriate amount and direction of power supply via lines 58-61 tomotor 55, which then rotates` in an appropriate direction to varyy theposition' v of valve element 5l and accordingly varies the vacuumapplied via` line 46 to portv 18 of the venous reservoir 15, therebycorrecting the condition of vacuum.

Manual. 75 of control 62 interrupts signal input at terminal 64-65 and.applies a manually adjusted voltage` signal which mayf be utilized inplace in the vacuum" responsive incoming signal of the strain gauge at'such terminals for manually adjusting vacuum via motor 55. In4 the eventof complete power failure of the vacuum system, vacuum may be controlledmanually at 64, see Figure 2.

Reference is now made to Figures 5 and 6, which. are; representative ofthe photo-electric arrangement for controlling liquid level in thevenous reservoir 15 and also; the liquid level in the oxygenatorportion. of. the apparaf tus, to which reference will later be made. InFigure 5. the reservoir R is representative of a container, either openor closed, in which liquid is maintained to level LL. With reference tothe venous reservoir 15, alreadyfde-v scribed, thev liquid level is at24. In respect to the oxy genator, to be described, theliquid level is124. These designations are shown in Figure 5`. To theside of thereservoir and below liquid level there is port 27 .cons nected to atubular sidev arm having a horizontal run 76 leading a vertical lighttransparent riser 77 .the top ne which is connected via run 78 to port79, which is above liquidlevel.V In the run 76 (and hence submerged)there 28 is suciently exible and of such thinness as to be) responsiveto even slight differences in head in reservoir Rand riser 77. Diaphragm28 is tubular and is of sufficient length that when it works back andforth it will suliice to permit equalization of liquid 80 to level LL,throughout the range of required equal level changes. On one side ofriser 77 is placed a light source 81 from the lens of which a parallelray light beam 82 is focused on transparent riser 77. On the other sideof riser 77 there is located photocell 86, the aperture 86A of which, isaligned with the axis of light beam 82.

The transparent tube 77 when empty of liquid 80, acts to disperse thelight beam to path 85, and the photocell 8'6 is not suflicientlyilluminated to provide an effective signal. When the liquid level risesin riser 77, the clear liquid and riser 77, in conjunction, act as alens which serves to focus the light rays along paths 84 and hence intocell 86, which accordingly produces an eiective signal. The diaphragm 2Sseparates the liquid B, which may be opaque or translucent such asblood, from the clear liquid 80. Hence the liquid level isphoto-electrically sensed regardless of the character of lighttransmissibility of liquid B, which here is blood. Riser 77 is'shown asbeing of circular cross-section, but can havea crosssection of lensshape.

Photo-electric liquid level signals are utilized attwo locations in thepresent apparatus. The first location is in respect to the venousreservoir 15, the liquid level of which is used for controlling theoperation of the occluder valve system 90, see Figures 1A, 1B, 3, 4,and' 7. The second location is in respect to the oxygenator 104, theliquid level of which is utilized to control the rate of operation ofthe artery pump 140 of the system. See Figures 1A, 1B and 8. Thespecific circuitries for these applications are described hereinafter.

Referring to Figures lA and 1B, from port 26 of reservoir 15 a plasticpipe 91 extends thru nip 93 of occluder valve mechanism 90 and thencethru T 92 and T 94 to and thru the recirculation pump 98 (of which tube91 is a part). At T 92 a branch extends thru shut-off valve 95 to donorblood supply reservoir 96 which is preferablyr calibrated for volume.From T 94 line plastic pipe 99 extends thru nip 100 of occluder valvemechanism 90 and thence to junction 101. From junction 94 the plastictubing 91 extends thru junction 174 and thence directly thru themechanism of recirculation pump 98, which like pump 40, is of the typeshown in Patents 2,659,368 and 2,705,493, thence directly thru the nipof high pressure stop switch 102 to inlet port 103 of the oxygenatorgenerally designated 104.

The oxygenator 104, per se, is of the design used by Gibbon. Briefly itconsists of a chamber 105 having a blood distribution space 106 at thetop equipped with a distributor shelf 108, which is provided with slitsin it thru which blood is iiowed onto a plurality of vertically disposedscreens 109 for distributing as uniformly as possible a layer tiow ofblood on the screens. An atmospheric vent port 110 at an upper part ofthe chamber is connected to vent line 111. It is noted, parenthetically,that line 111 should be carried safely outside the operating room since,during operation, it will contain a mixture of oxygen and ether inpossibly explosive proportions. Such vapors must therefore be safelyvented. At a lower part of the chamber 105 there is provided a gas inletline 112 which is connected at T 114 and Ithru pressure regulator valve115 to an oxygen supply 116 and thru branch 118 and regulator` valve 119to a carbon dioxide supply line 20. An ether inlet may be provided online 112, if desired. The normal liquid level of oxygenator 104 is at124. The liquid level control is by means of a side arm tube on the tank105, like that already described for venous reservoir 15. The side armtube starts at port 127, thence thru horizontal run 129 and verticallight transparent riser 132 and upper return 134 to tank 105. Horizontalrun 129 contains a very flexible diaphragm 128 which, like 28 of Figure5, is very flexible, thin and tubular, for the reasons stated relativeelement 28. Liquid 130 is transparent. Light source 133 is like source81 and photocell 131 is like photo-cell 86. The operation is alsosimilar. When the blood level 124 rises, the transparent liq uid 130also rises, and in cooperation with transparent riser 132, acts as alens to concentrate light upon cell 131, to produce a signal. When theblood level falls, liquid 130 also falls in tube 132, and then tempty orpartially empty tube 132 disperses the light from source 133 so that itdoes not fall upon cell 131 and the signal ceases or decreasessuliiciently so as not to be effective. The presence or absence of aprescribed signal valve at cell 131 is utilized for controlling theartery pump 140, which is caused to pump faster when the blood levelrises, and slower when the blood level falls.

The admixture of 02 and C02, oxygenates the hemoglobin of the blood inoxygenator 104, and ether may also be introduced for anesthesia, duringoperation. From the downwardly sloping bottom of oxygenator 105, andattached to port 121 is a plastic tube 122, extending through junctions101, 138 thence through and forming a part of pump generally designated140, thence thru the nip 141 of adjustable high pressure stop switch143, thence thru filter 142 and junction 144 to the artery cannulaconnection 145. From junction 144 a line extends through shut off valve146 to priming tank 147 of several liters capacity having a removabletop, and through which all liquids (except donor blood) are introducedinto the system. This may include sanitizing, and sterilizing liquids,saline solution and blood for priming the system. From tank 147 line 148extends thru valve 149 to junction 11. For priming the system the venousline 10 and artery line 145 are clamped off and valves 146 and 149 areopened until priming is completed. When operating, lines 10 and 145 areopened, valves 146 and 149 closed.

For measuring the percentage oxygen saturation of the hemoglobin of theblood llowing through the venous blood input line 10 and forcorrespondingly measuring such percentage concentration of the arterialblood delivered thru line 122-145 to the patient, there are usedcontinuously recording exi-meters made in accordance with U.S. Patents2,706,927 and Ser. No. 460,030 filed October 4, 1954. For sensingpurposes such oxi-meters require the liow of blood through a slenderplastic tube which runs through an instrument called a cuvette Two suchcuvettes are used here at 167 (for venous blood sensing) and 154 (forarterial blood sensing). The piping for these cuvettes and their valvingand flushing system, is as follows: For the arterial blood cuvette 154,the line starts at junction 138 and continues via twoposition valve 151through a slender plastic tube 152 which may extend straight through andform a part of the cuvette 154, thence through two-position valve 156and via line 157 to junction 140. For the venous blood, the pipingstarts at junction 12 and continues via line 16S, through two-positionvalve 164 and through a similar slender plastic tube 166 which extendsthrough and may form a part of cuvette 167, thence through twopositionvalve 169 and line 170 and to junction 174 on line 91. Each of thevalves 151 and 156 and the valves 164 and 169 can be set in thepositions shown, to permit flows of venous blood input and arterialblood output through the venous blood percentage-oxygen sensing` cuvette167 and the arterial blood percentage-oxygen;

sensingcuvette 154. respectively. `Iit addition when the' valves 151,156, 164 and 169 are placed in lthe'posi'- tions as shown at 151', 156',164 and 169', (as shown in the small sketches adjacent each. valve), thecuvettes may be flushed from saline solution flush tank 162, via line161 Vto T 159, and thence via line 158, valve 156 (set to position 156')cuvette tube 152, valve 151 (set to position 151') and drain line'172;also from junction 159, line 160, valve 164, (set to position 164'),tube166, valve 169 (set to position 169') to drain line` 171.

The adjustable over-pressure stop switches'103 and 143 are similar.vReferring to switch 193, the plastic tube 91 after passing thru pump98, is compressed slightly by the nip 102 which has asolidpad 102A onone side. of the plastic tube and a movable pad 102B which is biased byan adjustable spring (not shown) soas partially to squeeze the tubing91. VIn the normal position the movable pad 102B, which. is connected bya stem'to switch contact 175, holds the contact closed against, andcompletes an electric circuit between, contacts 176. When the pressurein tube 91 exceeds a predetermined limit it'will expand and cause thiscircuit to be opened. Similarly in respect to switch 143, tube 122 isheld in the nip 141 between stationary pad 143A and actuated by pressureresponsive pad 143B.,A PadA 143 is connected to switch 17S which serveseither' to bridge, and hence complete a circuit between, contacts 179,when pressure inv tube 122 is normal, or to open such contacts if thepressure exceeds a certain amount.

All of the pumps 40, 98 and 140 are similarly constructed, and are ofthe positive displacement tube and roller type, as shown in Patents2,659,368 and 2,705,- 493. Pumps 40 and also 9S. are constantly driven,each at a manually adjustable speed. Polyphase motor 45 drivesadjustable variable speed transmission 44 to rotate shaft 42 of pump 40.Polyphase motor 180 drives.

adjustable variable speed drive 181 to turn shaft 182A of pump 98. Thepower supply for motor 180, (oneJ or'more phases) is taken thru thecontacts 175--176 of switch 193 so as to stop motor 180 ifk excesspressure develops.

Referring to Figures 1A, 1B and 8, the shaft 184 of artery pump 140 isdriven by a variabie speed direct current motor 185 thru a speedreduction gear not shown. The motor 185 is a stock item in theservo-systems art, and is provided with a power supply and selfcontained magnetic amplifier system generally designated 1&6, also astock item. lt works as follows; \Vhen liquid level of blood rises inoxygenator 104, this causes clear liquid 130 to rise in tube 132, seeFigures 1A and 8, and concentrates light from lamp 133 upon photoceil131 to generate a signal which is applied to terminals 195 ofpreamplifier 190, the latter being supplied with 108V (positive) atterminal 191; 24V (negative) atterminal 192 and. grounded at 194, Theamplied, (in this illustration, liquid level increases), signal atterminalsA 189 of the pre-amplifier is applied to signal input terminals188 of the artery pump mo-tor control power supply and amplifier 136.Alternating current from lines L1 and L2, supplied to terminals 157 ismodulated and rectiiied by the signal at 13S and delivered as a directcurrent output at terminals 196, the voltage being a function of thesignal received at 188. Since the artery pump serves to increasewithdrawal of blood from the oxygenator 104, in response to increase or'blood level therein above level 124, such increase in level occasions anincrease in voltage (and hence speed of) motor 185, accordinglyy tocause pump 14u to withdraw blood from oxygenator 104 at an increasedrate, thereby reducing the level 124. The converse is true when theliquid level decreases. Overpressure safety switch 177-178 interruptsline 198 to motor 185 in the event of excessive pressure. inlineReferring to Figures 1A, and 1B, and.3, 4, and 7, these, shpwv'V-themotor and. controls -by means of whichthcY ingly Yactuated to squeezethe nip 93 to pinch tube 91 partially and restrict flow out of reservoir15, but at the same time to allow a substantially corresponding increaseof recirculatory flow. Hence, as tube 91 is partially restricted,y atthe same time the nip 100 opens, freeing;`

tube 99 to permit increased recirculation of blood. Similarly when vthephotocell, 86 senses an increase in level. of blood in reservoir 15 there"erse function is occa sioned, line 90" being squeezed less. to permitgreater blood withdrawal therethru and line 99 is squeezed more todecrease the rate of blood recirculation. This functioning is achievedhere, by a system in which cerv tain standard recording instrumentmotor, motor powery supply, amplifier and pontentiorneters are utilized.

Thus photocell 86 is connected to input terminals 202 of pre-amplier 200having 108 V. (positive) supply terminal 201;.24 V. (negative) supplyterminal 205 and ground 204. The amplified output is delivered at 206 asa positive voltage, the value ofY which is a function of the liquidlevel in tube 77. Such voltage signal at 206 is applied to contact 231of the single pole double pole switch 231--232-227, and with switchblade. 232 on terminal 231, such voltage of terminal 206 is applied toinput terminal 209 of a standard motor power supply and amplifier 207whichv is also a stock item. This amplifier power supply 207 has 110 VACinput at 211, ground 208, and a response input at 210 the voltage onwhich is brought into balance by the operation of a potentiometer 219which is. geared at 218 so as to bc driven'when valve gear 240 isrotated. The voltage.

produced at terminal 239 of the potentiometer 219 is a function of valveposition. The device (here valve 90) is driven by motor 215 from supply207 and the motor likewise turns potentiometer 219. The supply 207delivers polyphase power in appropriate phase and amount at. terminals212 for application to terminals 214 of motor 215, which in consequencerotates shaft 241 in one direction on the other, according to whetherthe signal input at 211 is more or less than the previous setting. l

As shown in Figures 3 and 4, shaft 216 of the motor is geared at 223 todrive gear 240 and hence rotate shaft 241 in one direction or the otheras shown by arrow 250. The walls 244 and 245 form the frame of theoccluder valve 90. Shaft 241 carries crank disk 241A which rotates in arecess in base 242. On disk 241A there is an upstanding crank pin 246 onwhich roller 247 turns.I The space between wall 244 and the periphery ofroller 247 forms the nip 93 thru which plastic tube 91 extends. Thespace between wall 245 and roller 247 forms the nip thru which plastictube 99 extends. When crank pin 246 and roller 247 are midway betweenwalls 244 and 245 both tubes 91 and 99 are equally compressed to anamount such that the sum of the cross-sectional areas of such twopartially compressed tubes about equals the cross-sectional area ofeither tube when not compressed. Rotation of shaft 240 clockwise fromthe mid-position additionally compresses tube 99 and releases tube 91,while rotation counterclockwise from the mid-position causes a reversedetect. As shown tube 99 is. open and tube 91 is compressed-tosubstantially its maximum extent.

The arrangement of valve 90 as shown has the characat its nip, will beabout constant, with the result thatl as liow thru one is decreased thrua given increment the flow thru the other will be increased thrusubstantially an equal increment, and vice versa.

To gear 240 there is mated gear 218 of a slide wire potentiometr 219having 108 V. D.C. input terminal 222, slider output terminal 230(voltage variable upon position) and a ground terminal. As shaft 241 andgear 240 are rotated gear 218 is also rotated and slider 229 (see Figure7) is moved to a position such that it provides a voltage output whichis representative of the angular position of rotation of shaft 241. Thevoltage of terminal 230 is applied back to response terminal 210 ofmotor power supply and amplifier unit 207. This unit 207 supplied powerto motor 215 in an amount and phase displacement appropriate to causerotation of valve 90 in an appropriate direction until the voltageapplied to response terminal 210 equals that at signal input terminal209. Then unit 207 discontinues the supply of power to motor 215 whichaccordingly ceases rotation until a diierent signal from photocell 86occasions -another setting of the occluder valve 90.

For manual operation of the occluder valve there is provided anotherpotentiometer 220 having a manually adjustable slider (and terminal) 226which is connected to terminal 227 of the double pole switch.

When contact 232 is on terminal 227, and slider contact 226 is manuallyadjusted the motor 215 and valve 90 will then follow to the positionoccasionad by position of adjustment of 226, rather than to beresponsive to the photocell 86. This facilitates manual operation duringinitial and final parts of the operation.

By way of specific illustration but not as a limitation, specificationof particular stock items may be mentioned as follows:

Relative Figures 3, 4 and 7:

Motor 215-Minneapolis Honeywell Motor, Catalogue Number 76750-3 1 MotorSupply and Amplifier 207 (for motor 215)- Minneapolis HoneywellCatalogue Number Relative Figure 7:

Pre Amplifier Tube-No. 6AQ5 Potentiometer 219- Beckman Instruments, Inc.

I-Ielipot Model 2500GZ; 2500 ohms Potentiometer 220-Ohmite Type A B;2500 ohms Relative Figures 1 and 8:

Pre Amplifier Tube-No. 6AQ5 Artery Pump Supply Ampliiier l-VickersMagnetic Amplifier Catalogue No. 2509 Relative Figures 1L and LR:

' Strain gauge Vacuum Sensing Unit 66-Statham Laboratories Catalogue No.P-0.4D-350 The operation of the herein described pump-oxygenatorapparatus is described in an article entitled Apparatus of the GibbonType for Mechanical Bypass of Heart and Lungs, by Richard E. .Tones etal., pages 10S-113, and in an article entitled Experiences with aHeart-Lung Bypass (Gibbon Type) in the Experimental Laboratory by DavidE. Donald et al., pages 1.13-1 15, which appeared in the Proceedings ofthe Staff Meetings of the Mayo Clinic, volume 30, Number 6, the samebeing incorporated herein by reference.

Initially the system may be full of saline solution and lines 10 and 145are closed by clamps, and valves 146 and 149 ore opened. Saline inreservoir 147 is circulated. Line 145 is opened and valve 146 closed, topump down the saline in tank 147. When the latter is empty blood isintroduced in tank 147 and the blood is pumped in behind the saline. Asthe saline is iiushed, line 145 is clamped and'valve 146 opened and thesystem then circulates blood, and operation is checked.

Pre-operative pressure measurement is taken by means surgical technique.Such pressure is variable as the heart pumps but is normally in therange of 2 to l0 mm. Hg pressure, positive. It has been found that goodvenous blood delivery from the patient during the oper ation, while thepatients heart and lungs are out of service, will be occasioned bymaintaining the central venous pressure of the patient a steady pressurewithin this range, preferably in the range of 2-5 mm. Hg pressurepositive. Now the physical elevation of the patient is usually a littlehigher than the venous reservoir 15. Also there is a pressure drop inthe cannula leading from the patient to tube 10 and thru the tube 10 toreservoir 15. The difference in static head and line pressure drop istaken into consideration and a carefully regulated pressure' (normallynegative) is maintained in reservoir 15 which,

blood that is delivered but not at such a rate that the central venouspressure would decrease below a pre-l scribed positive pressure, say of2 mm. Hg. In this way collapse of the patients veins is prevented andgood delivery of venous blood is obtained. The pressure in venousreservoir is normally 2-5 mm. Hg negative. All pressures are measuredrelative atmosphere pressure.

No attempt will here be made to describe surgical procedure, it beingsutlicient for present purposes, to mention that the venous blood isdelivered via lines 10 and via coronary sucker line 41. Pump 98ordinarily circulates blood from and to oxygenator 104 at a rateslightly in excess of the delivery rate via pump 140. The rate of pump98 may be adjusted by runs steadily at any position of adjustment.However, input to pump 98 may be entirely from recirculation line 99 orpredominately from venous blood supply line 91, or some from each, theproportion depending on the position of occluder valve 90. The rate ofinput via line 91 (to pump 98) is regulated by nip 93 of valve 90, whichis in turn responsive to the liquid level 24 in reservoir 15. As thelevel increases, nip 93 is opened and the venous inflow increases untilthe level 24 is again brought down. The system holds valve at a positionto maintain level 24- within close limits even though inflow from thepatient to reservoir 15, via line 10 may vary.

As a consequence of the foregoing, as the level 124 in the oxygenatorincreases, pump is speeded up to increase the rate of return to thepatient. Donor blood is introduced by opening valve 95.

As the system is taken oli, the levels 24 and 124 can be pumped down byswitching to manual control.

It is noted that in Figure lB, the mechanisms of valves 90 and 49-54 areshown in slightly dilerent mechanical forms than in the detailed viewsof Figures 3 and 4 and Figure 2, respectively. The specificillustrations of these components in Figure 1B may be regarded asmodified forms. v

In accordance with the provisions of the patent statutes, We have hereindescribed the principle of operation of this invention, together withthe elements which we now consider the best embodiments thereof, but wedesire to have it understood that the structures disclosed are onlyillustrative and the invention can be carried out by other means. Also,while it is designed to use the various features and elements in thecombinations and relations described, some of these may be altered andmodified and used separatelywithout interfering with the more generalresults outlined and the invention extends to such use within the scopeof the appended claims.

. As many apparently widely different embodiments of this invention maybe made without departing from the spirit and scope thereof, it is to beunderstood that we do not limit .ourselves to the specific,embodimentshereinn lil ' acclaim, is:

1.-...1;`he Vcombination comprising. an. oxygenator con-- Leinen havingmeans therein for exposing liquid to gases for absorption of gaseswithin. the container, said oxygenator container including gas inletport, liquid inlet port, and liquid outlet ports, circulation pump meanshaving a delivery port connected through a recirculation*` lino. to saidoxygenator liquid inlet port and an input port. connected to saidoxygenator outletA port for circulating liquid from the outlet port tothe inlet port of said oxygenator. container, a venous blood reservoirhaving an.

inlet. line and means connected to the reservoir for maintaining aprescribed reduced pressure therein for drawing blood through said inletline and into said reservoir, a.

venous line connecting said reservoir. directly to the input port; of.said circulation pump means and artery delivery means connected to. theoxygenator container outlet port for; withdrawing blood therefrom, said.combination is further. characterized in that it has means connected tosaid venous line and. recirculation line, said means being responsive tothe liquid level in said venous reservoir for. decreasing the flowthrough said venous line and increasing; the ow through saidrecirculation line when the blood level in said reservoir decreases andfor in- `creasing the ow through said venous line and decreasing portand a separated blood outlet port', the latter being connected to theinlet port of the venous blood `supply means, a coronary sucker lineconnectedI to the inlet port of the b1ood-air separator, and a pump insaid` coronary sucker line.

3i. The; combination comprising an oxygenator container having meanstherein for cxposingblood to gases for absorption therein orn gaseswithin the container, said oxygcnator having a gas inlet port and bloodinlet and outlet ports, venous blood supply means connected to saidblood inlet port and artery blood delivery means connected to saidoxygenatorl outlet port, a blood-air separator having an inlet port, aseparate air withdrawal portV and a separated blood outlet port, the.latter being connected to the inlet portY of the venous blood supplymeans, a coronary sucker line connected to the inlet port of theblood-air separator, and means. connected to. said' coronary sucker lineis provided for introducing antifoam material into the llow passingthrough said` coronary sucker line.

4; The combinetion comprising an oxygenator container having meanstherein for exposing blo^d to gases for absorption therein of gaseswithin the container, said oxygenator having a gas inlet port and bloodoutlet and inlet ports, venous blood supply means connected tosaid bloodinlet port and artery blood delivery means connected to said oxygenatoroutlet port, a blood-airseparator having an inlet port, a separate airwithdrawal port and a separated blood outlet port, the latter beingconnected to the inlet port of the venous blood supply means, and acoronary sucker line connected to the inlet port ofthe blood-airseparator, said apparatus being further characterized in that saidsep-arted blood outlet port. includes a vertically extendng portionwhich opens directly into said blood-air separator.

5. The combination comprising an oxvgenatorcontainer having meansthere`n for exposing blood to gases for absorption therein of'gaseswithin the container, said oxygenator `having a gas inet irrt andblood inlet and outl'etports, venous blood supply'nieans-connected tosaid blood inlet port: and artery blood delivery# com nected to. saidoxygenator outlet port, a blood-air separa. ratori having: an inletport, a separate. air withdrawaliport and a separated bloodoutlet port,the latter being cone. nected' to. the inlet port of the venous bloodsupply means, a coronary' sucker line connected to the inlet port of theblcod'air separator, and a positive displacement pumpinsaid coronarysucker line. 6. The combination comprising an oxygenator comtainerhaving means therein for exposing blood to gases` for absorption by theblood of gases within the container, said oxygenator having a gas inletport and blood inlet and outlet ports, venous blood supply meansconnected? to said oxygenator blood inlet port, said supply Incantivincluding a venous. blood reservoir having a blood inletf and a bloodoutlet, the latter being connected to the Oxy?. genatorV blood inletport, avacuum supply connected` to the venous blood reservoir, and avacuum regulator'fcon nected to the vacuum supply and responsive to thevacuum in said venous blood reservoir for maintaining at regu-latedamount of vacuum therein. Y

7. The combination of claim 6 further characterized'-in-4 that saidvacuum regulator includes a vacuum responsive means connected to thevenous blood reservoir for pro ducingan electrical signal which is afunction of the-`v amount of Vacuum in said reservoir and anelectrically operated vacuum control connected to said vacuum responsiveto said signal. 8. The combination comprising an oxygenator conftainerhaving means therein for exposing blood to gases? for absorption by theblood of gases within the containerg. said oxygenatcr container having agas inlet; port and` a" blood inlet port and a blood outletport,.veno'us l blood supply means including a venous bloodreservoirhaving a v-nous blood outlet connected to the bloodl inlet portoi' said oxygenator container and a coronary sinus reser Voir positionedadjacent the venous bloodV reservoir so as to permit a common normalblood levelto be. established in both reservoirs, a connection betweensaid reservoirs above said common blood level, a blood outletextendingfrom a lower part of the coronary sinus reservoir and connected to thevenous blood reservoir, a venous blood inlet for said venous bloodreservoir, Va coronary sinus inlet in said coronary sinus reservoir,said coronary sinus inlet being connected thru a gate for regulating.the flow thru said coronary sinus inlet to a prescribed volumetric rateand a vacuum source connection for said reservoirs.

9. The combination of claim 8 further charac'terizct` in that said gateis adjustable for varying the volumetric rate of bow through said gate.

10. The combination of claim 8 further characterized in that said gateis a rotary positive displacement pump..

1.1. The combination of claim 8 further characterized in that saidcoronary sinus inlet opens upwardly` into the COI'OIl'tI'y SlllUSYSTVOII'.

12'. The combination of claim 8 further characterized in thatsaidcoronary sinus inlet includes therein means'for treating the ilowtherethru with an anti-foam material'. I

13. The combination of claim 8 further characterized.

in thatV the outlet from said coronary sinus reservoir elol tendsdownwardly from said reservoir and thence coni' tinues to the venousblood reservoir.

1'4'. The combination ofclaim 8 further characterized. in that saidvenous blood reservoir is prvided with. af liquid level responsivedevice and means is provided and connected to the venous blood outlet ofsaid venous blood reservoir and to said o-xygenator blood inlet forregulating;Y the flow of blood from the venous blood reservoir forv`maintaining the normal blood level substantially constant'.

l5.. The combination of claim 8 further' characterized. inV that avacuum `line is connected to said Venous bloodnormal' blood level and isconnected to said'vacuuml'nc for closely regulating the vacuum appliedto said venous blood reservoir by said line. p

16. The combination of claim 8 further characterized in that a deliverypump is connected to the blood outlet port of said oxygenator containerfor withdrawing blood therefrom. i

17. The combination of claim 8 further characterized in that liquidlevel responsive means is connected to the oxygenator container, and adelivery pump is connected to the blood outlet port of said oxygenatorcontainer and 10 said delivery pump is connected to said liquid levelresponsive means for increasing the rate of delivery of said pump as theliquid level in said oxygenator increases and vice versa.

18. The combination of claim 8 further characterized in that a linehaving a circulation pump therein is connected between the blood inletand outlet ports of the oxygenator container.

References Cited in the le of this patent UNiTED STATES PATENTS2,659,368 Gibbon et a1 Nov. 17, 1953 2,689,565 Gobei s615621, 19542,705,493 Malniros et al Apr. 5, 1955 OTHER REFERENCES Gibbon: Surgery,Gynecology and Obstetrics, vo1.'69, No. 5, November 1939, pp. 602-614(pp. 603-608 relied on).

Clowes: Annals of Surgery, vol. 134, No. 6, December 1951, pp. 958-59.

Miller et al.: Journal of Thoracic Surgery, vol. 26, No. 6, December1953, pp. 60G-603, 616. (Available in Division 55.)

Jones et al.: Proceedings of the Staff Meeting, Mayo Clinic, vol. 30,No. 6, March 23, 1955, pp. 106-112. (Available in Scientic Library.)

UNirED STATES PATENT oFFIcE CERTIFICATE @F CRRECTIGN Patent No,299277582 March 8q 1960 John W Berkman et alo It is hereby certifiedthat error appears in the-printed specification of 'the above numberedpatenJ requiring correction and that the said Letters Patent should readas corrected below.

Column 6l line 181 for "and then tempty" read and the then empty columnQq line 29(l for "occasioned" read u occasioned line 681, for More" readare 5; column l2,1l line 28il before to Said signal insert means andSigned and sealed this 30th day of August 1960.,

(SEAL) Attest:

We C. Attesting Officer Commissioner of Patents

